Chances are, in a newly constructed home, you might not find the familiar copper piping underneath the kitchen sink. Instead, you may find crossed-linked polyethylene tubing, commonly referred to as PEX. Since being introduced into the U.S. market in the early 1980’s, PEX has made headway in the construction industry and is fully integrated in many new facilities across the country. Before its rise in popularity here in the states, PEX proved its versatility in Europe, where it was first created and put to use in the late 1960’s.
“Since the tubing is easily maneuvered into bends, there are few joints and fittings required, reducing the probability of leaks.”
PEX piping currently has three primary applications – radiant floor heating, snowmelt systems, and domestic water systems. The growth in the use of PEX, particularly for radiant flooring, was recently noted by the Radiant Panel Association. According to their survey, suppliers have sold approximately 20% more PEX each year for the past ten years. This tremendous growth has also spilled over into the plumbing industry. Plumbers are not only installing the tubing in the potable water systems of residential projects, but in commercial and industrial facilities as well.
There are several reasons for this rising trend in cross-linked polyethylene tubing. First and foremost, the flexibility of PEX allows it to be used in tightly constructed spaces. The tubing, sized in the same fashion as traditional copper piping, can be run like flexible conduit, through stud walls with various bends. PEX is often utilized in a manifold system for domestic water distribution. This system consists of two manifolds, one for hot water and one for cold water, each with many runs of PEX tapping off to individual plumbing fixtures.
Other benefits of the product include its low cost, longevity, and easy installation and maintenance. As the price of traditional copper piping has gone up, many contractors have been searching for more cost effective materials such as PEX. Since the tubing is easily maneuvered into bends, there are few joints and fittings required, reducing the probability of leaks. Installation time is therefore minimal. In addition, PEX is energy efficient when compared to copper because it has less heat loss.
There are, however, product limitations. There are still regions in the U.S. where installers are resistant to using PEX because it is unfamiliar and because copper’s long history of dependability is hard to overcome. In addition, PEX is susceptible to freezing at extreme temperatures, and sunlight degrades the quality of the tubing. In other words, PEX piping must not be exposed to UV rays for extended periods of time. For these reasons, PEX is mainly an indoor product, with the exception of being used for radiant floor heating and snowmelt systems, where it is concealed.
With the ever increasing demand for faster construction times and lower first costs, the use of PEX seems to be growing and has gained acceptance in the plumbing industry. The tubing is now approved in current editions of the national plumbing codes. Although, some local codes still reference older code editions, so use of PEX piping should be verified with individual jurisdictions.
– Matthew J. Stevens